Geometry Class Quiz on Angles and Shapes

Questions and Answers

At absolute zero (0K), pure Silicon and Germanium are classified as which of the following?

Conductors

Semiconductors (correct)

None

Insulators

In the calcium fluoride structure, the coordination numbers of cations and anions are:

6 and 6

8 and 4 (correct)

4 and 8

4 and 4

Which of the following structures is associated with a Frenkel defect?

Graphite

Diamond

NaBr

NaCl (correct)

In a tetragonal crystal structure, which of the following statements is true?

Two sides are equal, one is different Signup and view all the answers

In face-centered cubic (fcc) structures, cations occupy which kind of voids?

Alternate tetrahedral voids Signup and view all the answers

Which crystal structure has all sides equal and angles equal to 90 degrees?

α = β = γ = 90°; a = b = c Signup and view all the answers

Which of the following ionic compounds is expected to have the maximum distance between cations and anions?

CsF Signup and view all the answers

In solid alkali metal halides, what primarily causes the appearance of color?

F-centres Signup and view all the answers

Which structure is characterized by angles of 90 degrees and unequal sides?

α = β = γ = 90°; a = b ≠ c Signup and view all the answers

Which of the following types of materials exhibits ferrimagnetism?

MnO Signup and view all the answers

What is the coordination number of a gold atom in the crystal?

8 Signup and view all the answers

Which crystal system corresponds to the unit cell dimensions given by a = 0.387, b = 0.387, and c = 0.504 with α = β = 90° and γ = 120°?

Hexagonal Signup and view all the answers

What is the atomic mass of gold as mentioned in the provided content?

197 amu Signup and view all the answers

What is the density of gold as stated in the content?

19.4 g/cm³ Signup and view all the answers

In X-ray studies, how is the packing of atoms in a crystal of gold arranged?

In layers with identical every fourth layer Signup and view all the answers

What is the significance of the values α = β = 90° and γ = 120° in the context of crystal systems?

They determine the shape of the crystal and its symmetry Signup and view all the answers

What does a coordination number relate to in crystal structures?

The number of nearest neighbors surrounding an atom Signup and view all the answers

Which characteristic differentiates the hexagonal crystal system from others?

Contains symmetry of sixfold rotation Signup and view all the answers

What is the density of gold in grams per cubic centimeter (gcc)?

19.4 gcc Signup and view all the answers

For an fcc crystal with a density of 10.0 gcc and a cell edge of 200 pm, how many atoms are in 100 g of the crystal, expressed as x × 10^24?

5 Signup and view all the answers

What type of impurity should be added to silicon (Si) to create an n-type doped semiconductor?

Impurity with 5 valence electrons Signup and view all the answers

How many octahedral voids in a face-centered cubic (fcc) unit cell are not shared with other unit cells?

1 Signup and view all the answers

What is the relationship between the number of atoms in the unit cell of an fcc structure and its packing efficiency?

2 atoms with 74% packing efficiency Signup and view all the answers

What is the ratio of Fe3+ to Fe2+ ions in Fe0.9S?

0.28 Signup and view all the answers

In NaCl, how do the chloride ions occupy space?

Face-centered cubic (fcc) Signup and view all the answers

What is the fraction of total volume occupied by atoms in a simple cubic structure?

$\frac{\pi}{6}$ Signup and view all the answers

What is the correct expression for the interionic distance in a cesium chloride crystal?

a Signup and view all the answers

If NaCl is doped with 10^-4 mol% SrCl2, what is the effect on the concentration of cation vacancies?

It increases the concentration of cation vacancies Signup and view all the answers

Which of the following compounds has a ratio of Fe3+ to Fe2+ greater than 1?

Fe3O4 Signup and view all the answers

Which structure has the highest packing efficiency among the following?

Face-centered cubic Signup and view all the answers

In terms of ionic radii, what holds for cesium chloride?

The cation radius is less than the anion radius Signup and view all the answers

Study Notes

Solid State Chemistry Overview

Pure silicon and germanium at 0K are classified as semiconductors.
In the calcium fluoride structure, the coordination numbers for cations and anions are 8 and 4, respectively.

Crystal Structure Types

Tetragonal crystals have dimensions where a = b ≠ c and angles α = β = γ = 90°.
In NaCl, the chloride ions occupy a face-centered cubic (FCC) arrangement.
The interionic distance for cesium chloride crystals can be expressed as a.

Ionic Compounds and Defects

The maximum distance between cations and anions occurs in LiI.
Frenkel defects are observed in NaBr, while Schottky defects are linked to ionic compounds in general.

Properties of Alkali Metal Halides

The color appearance in solid alkali metal halides is commonly due to F-centers.

Magnetism and Ion Ratios

Ferrimagnetism is demonstrated by Fe3O4, while the ratio of Fe3+ to Fe2+ ions in Fe0.9S is 0.28.

Volume Occupation and Doping

The total volume occupied by atoms in a simple cubic cell is π/6.
Doping NaCl with 10⁻⁴ mol% SrCl₂ increases the concentration of cation vacancies.

Crystallography and Density

The crystal system for a compound with lattice parameters a = b = 0.387 nm, c = 0.504 nm, α = β = 90°, and γ = 120° is hexagonal.
In FCC crystals, there are 1 octahedral void not shared with other unit cells per unit cell.

Semiconductor Doping

To create n-type doped semiconductors, impurities with five valence electrons should be added to silicon.

Other Noteworthy Facts

The density of gold is 19.4 g/cm³ and its atomic mass is 197 amu.
The number of atoms in a 100 g FCC crystal with a density of 10.0 g/cm³ and cell edge of 200 pm equals 5 × 10²⁴.

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Description

This quiz tests your knowledge of geometric shapes and angles. You will analyze various conditions of angles and sides to identify the type of shape described. Perfect for students studying geometry in depth.